Port 1375: Bytex — A ghost in the registry

What This Port Is

Port 1375 is registered in IANA's official registry under the name "bytex".¹ Both TCP and UDP variants exist. But if you search for what Bytex actually did, you'll find almost nothing. The protocol itself has been lost to time.

The Ghost Story

Bytex Corporation was a real company in the 1990s. They manufactured network switching systems—the kind that routed traffic between mainframe computers in wide area networks.² They built "electronic matrix switching systems" that provided centralized access to data flowing through communication lines.

At some point, they registered port 1375 for their protocol. Then the company faded. The switching systems were replaced. The protocol stopped being used. And now we're left with just a name in a registry and a port number that almost nothing listens on.

Why Ghost Ports Matter

The registered ports range (1024-49151) is full of stories like this. Companies register ports for proprietary protocols, then disappear. Standards are proposed, never adopted, but the port remains reserved. Someone had a plan that never materialized.

Port 1375 is one of thousands of registered ports where nothing actually runs. And that's important to understand: port registration doesn't mean active use. It just means someone, at some point, claimed this number for a specific purpose.

What Range This Port Belongs To

Ports are divided into three ranges:

• Well-known ports (0-1023): Reserved for core Internet services, require root/admin privileges
• Registered ports (1024-49151): This is where port 1375 lives—registered with IANA but doesn't require special privileges
• Dynamic/ephemeral ports (49152-65535): Temporary ports assigned by your operating system

Port 1375 sits in the middle range. Anyone can register a port here by filing an application with IANA. But registration doesn't guarantee the port will ever be used, or that anyone will remember what it was for decades later.

How to Check What's Listening

Even though port 1375's original protocol is forgotten, something else might be using it on your system. Here's how to check:

On Linux/macOS:

# See what's listening on port 1375
sudo lsof -i :1375

# Or use netstat
sudo netstat -tlnp | grep 1375

On Windows:

# Check port 1375
netstat -ano | findstr :1375

If something appears, it's probably not Bytex. It's likely a modern application that chose this port because it was available and unassigned in practice.

The Real Lesson

Port 1375 teaches something important: the Internet is full of abandoned infrastructure. Registry entries that outlive the systems they described. Names that no longer mean anything. Numbers reserved for protocols that nobody runs.

This isn't a failure—it's archaeology. Every ghost port is evidence that someone built something, registered it officially, and then moved on. The port number remains, a small memorial to a protocol that once mattered enough to claim a permanent address.

Most ports tell stories of protocols we still use daily. Port 1375 tells a different story: how quickly a network protocol can be forgotten, even when its port number lives on.